Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Using single quantum dots to probe nanowires: Lighting up plasmonic wires with nanometer accuracy

 (a) This is an optical image of the microfluidic crossed-channel device. Flow in the center control region (dashed circle) is manipulated in two dimensions by 4 external electrodes (not shown). Scale bar is 500 μm. (b) This is a schematic of the positioning and imaging technique. A single QD is driven along a trajectory close to the wire by flow control. The inset shows a microcope image of a typical nanowire with 1 μm scale bar.

Credit: JQI
(a) This is an optical image of the microfluidic crossed-channel device. Flow in the center control region (dashed circle) is manipulated in two dimensions by 4 external electrodes (not shown). Scale bar is 500 μm. (b) This is a schematic of the positioning and imaging technique. A single QD is driven along a trajectory close to the wire by flow control. The inset shows a microcope image of a typical nanowire with 1 μm scale bar.

Credit: JQI

Abstract:
Modern telecommunications happens because of fast electrons and fast photons. Can it get better? Can Moore's law---the doubling of computing power ever 18 months or so---be sustained? Can the compactness (nm-scale components) of electronics be combined with the speed of photonics? Well, one such hybrid approach is being explored at the Joint Quantum Institute (*), where scientists bring together three marvelous physics research fields: microfluidics, quantum dots, and plasmonics to probe and study optical nanostructures with spatial accuracy as fine as 12 nm.

Using single quantum dots to probe nanowires: Lighting up plasmonic wires with nanometer accuracy

College Park, MD | Posted on February 5th, 2013

PLASMONICS

When light strikes a strip of metal an electron wave can be excited in the surface. Is this "surface plasmon" a bit of light or electricity. Well, it's a bit of both. The wavelength of this electromagnetic wave is shorter and the energy density higher than that of the incoming laser light; the plasmon is thus tightly localized light constrained to propagate along the meal surface. The science of "plasmonics" has arisen to capitalize on various imaging, sensing, and processing abilities inherent in plasmons. To start with, though, one needs to know exactly what happens at that laser-excited metallic surface. That light is converted into the plasmonic wave; later the energy can be reconverted into light.

Here's where the JQI experiment comes in. The main result of the work, published February 5 in the journal Nature Communications, is to provide a map showing how the metal strip, in this case a silver wire 4 microns long and 100 nm wide, lights up.

MICROFLUIDICS AND QUANTUM DOTS

The other two chief components of the experiment, in addition to plasmonics, are microfluidics and quantum dots. Microfluidics, a relatively new science all by itself, features the movement of nanoliter volumes of fluids through channels defined on microchips, analogous to the conducting paths strung across microprocessors for carrying electrical currents. Quantum dots, nanometer-sized semiconductor balls, are tailored to possess a specified set of allowed energy states; in effect the dots are artificial atoms that can be moved around. In the JQI experiment the 10-nm-wide dots (the important cadmium-selenide layer is only 3 nm thick) float in a fluid whose flow can be controlled by varying an applied voltage. The dots are drawn up close to the nanowire as if they were mines next to a submarine.

Indeed the dot is there precisely to excite the wire. The dot is fluorescence machine---in a loose sense a nanoscopic lightbulb. Striking it with green laser light, it quickly re-emits red light (one photon at a time), and it is this radiation which excites waves in the nearby wire, which acts like an antenna. But the interaction is a two-way street; the dot's emissions will vary depending on where along the length of the wire it is; the end of the wire (like any pointy lightning rod on a barn) is where electrical fields are highest and this attracts the most emission from the dot.

A CCD camera captures light coming from the dots and from the wire. The camera qualities, the optical properties of the dot, the careful positioning of the dot, and the shape and purity of the nanowire combine to provide an image of the electric field intensity of the nanowire with 12-nm accuracy. The intensity map shows that the input red light from the quantum dot (wavelength of 620 nm) has effectively been transformed into a plasmonic wavelength of 320 nm.

Chad Ropp is a graduate student working on the project and the lead author on the paper. "Plasmonic maps have been resolved before, but the quantum mechanical interactions with a single emitter have not, and not with this degree of accuracy," said Ropp.

POSSIBLE APPLICATIONS

In an actual device, the quantum dot could be replaced by a bio-particle which could be identified through the nanowire's observed effect on particle's emissions. Or the dot-wire duo could be combined in various configurations as plasmonic equivalents of electronic circuit components. Other uses for this kind of nanowire setup might exploit the high energy density in the plasmonic state to support nonlinear effects. This could enable the nanowire-dot combination to operate as an optical transistor.

"Nanoscale imaging and spontaneous emission control with a single nano-positioned quantum dot," Chad Ropp, Zachary Cummins, Sanghee Nah, John T. Fourkas, Benjamin Shapiro, Edo Waks, Nature Communications, paper published online 5 February 2013. Chad Ropp, , 301-405-5010

####

About Joint Quantum Institute
The Joint Quantum Institute is operated jointly by the National Institute of Standards and Technology in Gaithersburg, MD and the University of Maryland in College Park.

For more information, please click here

Contacts:
Phillip F. Schewe

301-405-0989

Copyright © Joint Quantum Institute

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Laboratories

RMIT delivers $30m boost to micro and nano-tech August 26th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

News and information

RMIT delivers $30m boost to micro and nano-tech August 26th, 2014

Creation of a Highly Efficient Technique to Develop Low-Friction Materials Which Are Drawing Attention in Association with Energy Issues August 26th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Microfluidics/Nanofluidics

Novel chip-based platform could simplify measurements of single molecules: A nanopore-gated optofluidic chip combines electrical and optical measurements of single molecules onto a single platform August 14th, 2014

Blacktrace Holdings Ltd. to in-license PerkinElmer Technology August 8th, 2014

“Active” surfaces control what’s on them: Researchers develop treated surfaces that can actively control how fluids or particles move August 6th, 2014

Dolomite announces exclusive agreement for the sale of compact microfluidic pressure and vacuum pumps for pneumatic control systems in microfluidics, chemistry and mechatronics August 5th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Introducing the multi-tasking nanoparticle: Versatile particles offer a wide variety of diagnostic and therapeutic applications August 26th, 2014

Scientists craft atomically seamless, thinnest-possible semiconductor junctions August 26th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

X-ray Laser Probes Tiny Quantum Tornadoes in Superfluid Droplets: SLAC Experiment Reveals Mysterious Order in Liquid Helium August 25th, 2014

Chip Technology

Scientists craft atomically seamless, thinnest-possible semiconductor junctions August 26th, 2014

RMIT delivers $30m boost to micro and nano-tech August 26th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Symphony of nanoplasmonic and optical resonators leads to magnificent laser-like light emission August 26th, 2014

Optical Computing

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

NUS scientists use low cost technique to improve properties and functions of nanomaterials: By 'drawing' micropatterns on nanomaterials using a focused laser beam, scientists could modify properties of nanomaterials for effective applications in photonic and optoelectric applicat July 22nd, 2014

New NIST metamaterial gives light a one-way ticket July 2nd, 2014

Don't blink! NIST studies why quantum dots suffer from 'fluorescence intermittency' May 22nd, 2014

Discoveries

Scientists craft atomically seamless, thinnest-possible semiconductor junctions August 26th, 2014

Creation of a Highly Efficient Technique to Develop Low-Friction Materials Which Are Drawing Attention in Association with Energy Issues August 26th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Symphony of nanoplasmonic and optical resonators leads to magnificent laser-like light emission August 26th, 2014

Announcements

RMIT delivers $30m boost to micro and nano-tech August 26th, 2014

Creation of a Highly Efficient Technique to Develop Low-Friction Materials Which Are Drawing Attention in Association with Energy Issues August 26th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Symphony of nanoplasmonic and optical resonators leads to magnificent laser-like light emission August 26th, 2014

Quantum Dots/Rods

Interaction between Drug, DNA for Designing Anticancer Drugs Studied in Iran August 17th, 2014

NANOPARTICLES INDIA August 8th, 2014

Researchers create quantum dots with single-atom precision June 30th, 2014

New Los Alamos Approach May Be Key to Quantum Dot Solar Cells With Real Gains in Efficiency: Nanoengineering Boosts Carrier Multiplication in Quantum Dots June 19th, 2014

Photonics/Optics/Lasers

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Symphony of nanoplasmonic and optical resonators leads to magnificent laser-like light emission August 26th, 2014

Biomimetic photodetector 'sees' in color: Rice lab uses CMOS-compatible aluminum for on-chip color detection August 25th, 2014

Ultra-short pulse lasers & Positioning August 21st, 2014

Alliances/Partnerships/Distributorships

JPK expands availability of instrumentation in the USA – appointing new distributors – launched a new web site to support the US market - AFM now available to US users August 26th, 2014

Sunblock poses potential hazard to sea life August 20th, 2014

SouthWest NanoTechnologies Appoints Matteson-Ridolfi for U.S. Distribution of its SMW™ Specialty Multiwall Carbon Nanotubes August 13th, 2014

Could hemp nanosheets topple graphene for making the ideal supercapacitor? August 12th, 2014

Research partnerships

Scientists craft atomically seamless, thinnest-possible semiconductor junctions August 26th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Symphony of nanoplasmonic and optical resonators leads to magnificent laser-like light emission August 26th, 2014

Picosun joins forces with IMEC for novel, industrial ALD applications August 25th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE